“Not true. What I’m saying is only on the tzad that techeiles is legitimately being suppressed. If Rabbeinu Yonah held, in his day and age, that it was improper, fine. But that is no raya to us bizman hazeh.”
To make such a claim you would have to explain what changed from then to bizman hazeh.
That’s not true. This svara of “times changed” is one of the most fundemental and nuanced svaras dealing with how to properly adapt mesorah to constantly changing times. It is obvious to even a five year old that there have been many significant changes and evolutions across a broad spectrum of inyanim, many of which are plausibly relevant. The R”Y’s who follow the mesoras have to be able to answer it though. So ask them.